| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a glass pipe having a high precision outer diameter with a high yield by improving the stability of controlling the outer diameter. SOLUTION: A method for manufacturing the glass pipe comprises drawing a glass pipe G by moving both ends of the pipe G relatively while heating and softening the pipe G from one end side toward the other end side. The method includes: a constant pressure drawing process for increasing relative moving speed of both ends of the glass pipe G to a predetermined feeding speed V1 and taking-up speed V2 which are calculated from the initial cross sectional area calculated from the outer diameter and the inner diameter of the glass pipe G and the cross sectional area after drawing, calculated from the outer diameter and the inner diameter of a drawing target; a pressure-drawing process for making the drawn outer diameter value Dpv to a target outer diameter value Dsp or higher by raising the inner pressure of the glass pipe G; and an inner pressure control drawing process for controlling the inner pressure based on the drawn outer diameter value Dpv so that the drawn outer diameter value Dpv becomes the target outer diameter value Dsp, after the drawn outer diameter value Dpv has been made to the target outer diameter value Dsp or higher. COPYRIGHT: (C)2008,JPO&INPIT
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